Re: amd64 kernel, i386 userland

[manu%netbsd.org@localhost (Emmanuel Dreyfus)]

Christos Zoulas <christos%astron.com@localhost> wrote:

> I think EMUL_NATIVEROOT is better, since everything starts with EMUL?

We'd get this, with the option documentation:

Index: sys/kern/kern_exec.c
===================================================================
RCS file: /cvsroot/src/sys/kern/kern_exec.c,v
retrieving revision 1.369
diff -U 4 -r1.369 kern_exec.c
--- sys/kern/kern_exec.c        3 Jan 2014 15:49:49 -0000       1.369
+++ sys/kern/kern_exec.c        25 Jan 2014 16:13:13 -0000
@@ -177,9 +177,13 @@
 
 /* NetBSD emul struct */
 struct emul emul_netbsd = {
        .e_name =               "netbsd",
+#ifdef EMUL_NATIVEROOT
+       .e_path =               EMUL_NATIVEROOT,
+#else
        .e_path =               NULL,
+#endif
 #ifndef __HAVE_MINIMAL_EMUL
        .e_flags =              EMUL_HAS_SYS___syscall,
        .e_errno =              NULL,
        .e_nosys =              SYS_syscall,
Index: share/man/man4/options.4
===================================================================
RCS file: /cvsroot/src/share/man/man4/options.4,v
retrieving revision 1.432
diff -U 4 -r1.432 options.4
--- share/man/man4/options.4    13 Oct 2013 22:34:13 -0000      1.432
+++ share/man/man4/options.4    25 Jan 2014 16:13:13 -0000
@@ -449,8 +449,23 @@
 .Va struct stat
 are adjusted and some binaries which use
 .Xr sysctl 3
 to retrieve network details would not work properly.
+.It Cd options EMUL_NATIVEROOT=string
+Just like emulated binaries first try to lookup files in 
+an emulation root (e.g.:
+.Pa /emul/linux )
+before looking them up in real root, this option cause native
+binaries to first look up files in an "emulation" directory too.
+This can be useful to test an amd64 kernel on top of an i386 system
+prior full migration: by unpacking the amd64 distribution in e.g.
+.Pa /emul/netbsd64 
+and specifying that location as
+.Cd EMUL_NATIVEROOT ,
+native amd64 binaries can be run while the root filesystem remains
+populated with i386 binaries. Beware of 
+.Pa /dev
+incompatibilities between i386 and amd64 if you do this.
 .It Cd options EXEC_ELF_NOTELESS
 Run unidentified ELF binaries as
 .Nx
 binaries.

-- 
Emmanuel Dreyfus
http://hcpnet.free.fr/pubz
manu%netbsd.org@localhost